The present invention relates to the core material of a magnetic head used in a magnetic disk apparatus or video tape recorder. More particularly, the invention relates to a ferromagnetic film having high saturation magnetic flux density, high permeability, a low magnetostriction constant and high corrosion resistance, and a magnetic head using the ferromagnetic film.
The magnetic recording technology has made remarkable progress in recent years, and the recording density in magnetic recording is now being increased to make a home video tape recorder small in size and weight, and to increase the storage capacity of a magnetic disk. In order to increase the recording density, a ferromagnetic film used in a magnetic head is required to have high saturation magnetic flux density so that a high density recording operation can be performed for a recording medium having high coercivity.
Further, the material of a ferromagnetic film used in a magnetic head is required to have high permeability to improve the recording/reproducing efficiency. In order to keep the recording/reproducing efficiency stable, it is preferable that the above material have a magnetostriction constant nearly equal to zero.
As a magnetic material having such magnetic characteristics, an Fe-Al-Si alloy (the so-called "sendust") disclosed in JP-A-60-74,110 and an Fe-Si alloy disclosed in JP-A-52-112,797 (corresponding to U.S. application Ser. No. 662,198 filed on Feb. 26, 1976 and assigned to IBM) and JP-A-59-182,938, have been developed. Each of these alloys contains iron as its main component, and has a high saturation magnetic flux density. These alloys can be used as a magnetic head material.
However, the Fe-Al-Si alloy has a relatively low saturation magnetic flux density of about 10 KG. Further, the Fe-Si alloy has a high saturation magnetic flux density of 18 KG, but is low in corrosion resistance. When ruthenium (Ru) or the like is added to the Fe-Si alloy to improve the corrosion resistance, the saturation magnetic flux density of the Fe-Si alloy is reduced to about 14 KG.